FIG. 1 diagrammatically illustrates the configuration of a typical multi-panel residential garage door 10, as comprising a plurality of panels 11 (usually made of galvanized steel or fiberglass), which are hinged together at hinge joints 13. The hinge joints are equipped with side wheels or rollers 15 that ride in a pair of guide tracks 17, 18 that extend along opposite sides of the garage door opening 19. The guide tracks 17, 18 are usually anchored (e.g., bolted) to wall regions 21 and 22 of the garage adjacent to the opening 19 and attached via brackets 25 to the ceiling 26. The door 10 may be opened and closed either by hand or by way of an automated garage door translation device, such as may be mounted to the ceiling and attached to the topmost one of the door panels 11.
As described in DeCola et al, U.S. Pat. No. 5,620,038, entitled: "System for Bracing Garage Door Against Hurricane Force Winds," (assigned to the assignee of the present application, and the disclosure of which is incorporated herein), when a multi-panel garage door is exposed to high velocity winds of a violent storm, such as a hurricane, the door panels 11 have a tendency to separate from the guide tracks 17, 18 as a result of continued flexing of the panels and fatigue of the tracks themselves. This repeated flexing causes the side wheels 15 to become detached from the tracks 17, 18, so that the ends of panels 11 become warped, allowing wind to enter the garage and literally rip or `peel` the door away from the garage door opening 19. Once the garage and adjacent structure has been blown out, the ceiling of the garage and adjacent structure are no longer protected from the extremely high velocity winds of the storm, and it is simply a matter of time before the roof blows off, causing the entire structure to be destroyed.
Follow-up investigation to the widespread damage to residential buildings in south Florida by hurricane Andrew in 1992 has revealed that had garage doors been reinforced against such separation from the guide tracks, and not blown out, the full force of the hurricane would not have been able to enter many of the destroyed houses. As a result of this investigation, homebuilders in coastal areas of south Florida are required to provide some form of hurricane reinforcement for their garage doors. Recommendations of how to accomplish this have usually involved the installation of (metal or wooden) girts that extend horizontally across each panel. Such girts are intended to stiffen the panels and prevent their oscillatory motion that leads to the destructive separation from the tracks.
Unfortunately, such stiffening panels add considerable weight to the door, requiring adjustments of both the lifting coil spring and of the drive of the automated garage door translation mechanism. Moreover, even with such adjustment, the substantial weight of the girts, for which neither the door nor the automated translation mechanisms were originally designed, leads to further wear and tear of the automatic garage door opener. Yet, even with such stiffeners, the fundamental problem they are intended to solve is not remedied, since they do not prevent torquing of the panels at the point of attachment of the door to the tracks, and do not effectively relieve the wind load placed on the entire garage door opening. The girts are unable to prevent torquing since they extend horizontally - making them parallel to joint lines between panels. Such an orientation provides axes of rotation, about which the panels are torqued when subjected to high velocity winds. The girts provide neither reinforcement nor a separation barrier along the lengths of the tracks, nor do they make the door a wind-loadable door.
Advantageously, the door-bracing system described in the above-reference ('038) patent remedies these shortcomings, by means of a door bracing system that contains a plurality of door-stiffening column members that are installed between associated upper mounting brackets above the garage opening and lower mounting brackets affixed to the garage floor. The door bracing system also includes deflection brackets which attach the door panel hinge joints to the column members, so that the entire vertical extent of the garage door is effectively braced against high velocity winds, and thereby prevented from separating along the guide tracks.